I picked up some black knitting in thread yesterday at Spotlight for $4.19 (different brand to the white and same length).
However it is black because it has a very fine black normal looking thread wrapped around a white stretchy thread, this makes it look thicker, rough and a little furry.
I checked what it would look like on poles for black PVC coated power lines and as old rusty barbed wire (rough effect) on a fence but in my mind it failed on all counts.
Also, it can't be made to sag as the black fine thread wrinkles up.
So it is a no go, back to the white.